Hacksaw-machine.



L. M. FAIRBANKS. HACKSAW MACHINE. APPLICATION FILED 001*.31, 1911.

Patented June 4, 1912.

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HAGKSAW MACHINE. APPLICATION FILED 00131, 1911 1,028,342, ,Patented June 4,1912.

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LEONARD M. FAIRBANKS, OF NEW HAVEN, CONNECTICUT, ASSIGNOR TO THE HENRY Gr. THOMPSON & SON COMPANY, OF NEW HAVEN, CONNECTICUT, A CORPORATION OF CONNECTICUT.

HACKSAW-MACI-IINE.

Specification of Letters Patent.

Application filed October 31, 1911.

Patented June 4, 1912.

Serial No. 657,764.

To all whom, it may concern:

Be it known that I, LEONARD M. FAIR- BANKS, a citizen of the United States, re-

siding at New Haven, in the county of New Haven, State of Connecticut, have invented certain new and useful Improvements in Hacksaw-Machines, of which the following is a specification, accompanied by drawings.

The invention relates to hack saw machines having means for lifting the saw on the return stroke, and its object is to improve such action and render the lifting more smooth and certain.

In the drawings Figure 1 represents a side View of a hack saw machine provided with my invention, Fig. 2 a top view, and Fig. 3 an end view of the same with parts omitted; Fig. 4 is a sideview of a cam thereof detached; Fig. 5 a perspective View of the cam-actuated lever of the lifting mechanism; Fig. 6 represents a side viewon larger scale of the clamping jaws, Fig. 7 an end View, and Fig. 8 a top view of the same; Fig. 9 shows a section seen on plane 99 of Fig. 6; Fig. 10 represents an inside face view of one of the clamping jaws; Fig. 11 shows a sectional view on plane 1111 of Fig. 9.

In hack saw machines it is desirable'that after each cutting stroke the saw be lifted to save wear on the teeth in the back stroke and returned quickly to its initial cutting position. An example of this is seen in Lanfair Patent 935,665, October 5th, 1909, in relation to whch I illustrate the application of the present improvements, though not limited to the details thereof.

In the type of machine shown, the saw is raised at the end of each stroke by means of a frictionally clamped lifting bar attached to the guide bar of the saw frame. This lifting bar is clamped, raised and lowcred, and then the friction is released so that the saw may bear down and cut freely in its cutting stroke. Under the present improvements, the two coacting jaws have self-adjusting clamping surfaces which clamp the said lifting bar while allowing some slight angular movement of the bar in the jaws without danger of slipping. The engaging faces of the clamping and lifting jaws are so constructed that while engaging and holding the lifting bar they are free to rock in every direction, and also to turn to allow angular movement of the bar, so that they automatically adjust their positions and retain true contact against the friction surface of the bar. Furthermore, when the lifting bar is released from the clamping pressure, the engaging faces afford smooth surfaces on which the bar slides with but little friction.

In the drawings the main bed or frame 2 supported by the legs 3 has mounted at one of its ends a block 4. From block 4 rise two bearing walls 5 and 6, and at one side of said walls extends the tubular bearing 7. Through the walls 5 and 6 runs a shaft 8 carrying a large gear wheel 9, which gear wheel meshes with the pinion 10. Driving shaft 11 of pinion 10 is driven by the belt pulley 12, and carries the usual loose pulley 13. On an axis parallel to but below that of shaft 8 is the shaft 14, which shaft runs in the tubular bearing 7 and carries at one extremity disk 15. A pitman 16, pinned at one of its extremities to disk 15, is at its other extremity pivotally connected to saw frame 17, carrying the hack saw blade 18, to actuate the same.

Attached to saw frame 17 are the guide or clip plates 19 and 20 which surround and slide upon the guide bar 21. The arm 22, which carries the guide bar 21, is mounted on shaft '8 between the walls 5 and 6. A rod 24 and adjustable weight 25 is attached to arm 22.

The stud or wrist pin 26 connects pitman 16 to disk 15 and extends into the groove 27 in the cam 28 turning with gear 9 and shaft 8. The sliding of stud 26 in the groove 27 controls the revolution of disk 15. During one portion of the stroke stud 26 is near one extremity of groove 27, while at another portion of the stroke stud 26 is near the other extremity of groove 27, which provides for the relatively quick return stroke of the saw, as will be understood.

Pivoted to the guide bar 21 is the lifting bar 29 for raising it, for example, during the back stroke. This bar extends down between clamping and lifting jaws 80, 31. The jaw 31 is carried by the jaw 30 and is slightly adjustable relatively thereto by the adjusting screw 32 by which the tightness of the clamping action of the jaws upon the lifting bar can be adjusted. The jaw 31 has a slight play upon the screw 32 which is screw-threaded in the jaw 30. The motion of the jaws relative to each other is guided by the guide pin 33 secured in the jaw 30 and extending into the correspond ing guide hole in the other jaw 31. Each of the jaws is provided with a smooth-faced contact button 35 approximately fitting a circular recess in the jaw but free to rock and turn therein. These buttons are supported from behind on adjustable screws 36 threaded through the jaws and provided with set-nuts 37. The smooth faces of these buttons bear against the respective sides of the lifting bar 29 and by adjusting the screws 36 the interval between the opposed but-tons is adjustable and the wear upon the buttons may be compensated for.

The recesses which receive the buttons 35 are placed at the narrowest part of the ver tical channels 34, which afford clearances for the lifting bar 29 between the faces of the jaws. These channels are narrowest where the buttons are inserted and enlarged above and below, and by approximately fitting the bar 29 they prevent its getting out of place when the clamping pressure of the buttons is released. It will be seen presently that in the lifting action when the buttons are clamped against the lifting bar 29 there is some angular movement between the bar and the jaws. The buttons by rotating against the ends of the screws 36 allow for this, whiletheir ability to rock permits them to make accurate contact upon the smooth surfaces of the bar 29 on each side.

The jaw 30 is pivoted to the bed of the machine by a pivot pin 38 extending through a pivot hole 39 in the jaw. The downward movement of the jaws is limited by the adjustable screw-stop 40, which is in line to rest upon a suitably rigid portion of the 7 machine, as, for example, the crosslever 42. The adjustment of the jaws should be such that when so supported on the stop 40 the lifting bar can just slide freely between the buttons and the a-ws standing slightly apart, as seen in Figs. 8 and 9. The end portions of the jaws remote from the pivot hole 39 are beveled on the sides slightly, as at 43. These beveled faces engagecorrespondingly beveled faces in the notched end 45 (see Fig. 5) of cam-operated lever 46 pivoted to the frame as shown. The other end of this lever is pressed by spring 47 against the periphery of the cam 28, which is designed so as to raise the notched end 45 of the lever 46 just before and during the return stroke of the saw. When the saw is cutting, the notched end of the lever does not support the clamping jaws 30, 31, but when the notched end 45 of the lever rises in engaging the beveled faces 43 of the jaws, itfirstrclamps the jaws and then raises them, thus raising the lifting bar 29, which is clamped between the buttons, When. the notched end 45 descends, it lowers the jaws until by the striking of the screw-stop 40 the weight of the jaws is taken from the notched and beveled faces, whereupon the further descent of the notched lever end releases the jaws. It will be seen that as the clamping jaws pivot on the pin 38 in their vertical motion and the lifting bar 29 is pivoted to the guide arm 21, there is an. angular motion between the further motion of the lever raises the clamping jaws, and the buttons raise the lifting bar and partake with it the slight angular movement between the lifting bar and the clamping jaws. Thus, the buttons remain in frictional repose against the surface'of the lifting bar andv eliminate the tendency to slip, due to said angular movement. The contact between the buttons and the screws 36 which support them from the rear being practically in the center of the buttons allows the buttons to turn with very little resistance upon the ends of the screws 36. In the descending movement the action is similar until the descent of the jaws is checked by the stop 40, which releases the clamping pressure as already explained and allows the bar to, slide freely downward to bring the saw into action.

I claim the following:

1. In a hack saw machine the combination of the saw lifting bar having one or more smooth faces and clamping and lifting means for clamping, lifting and releasingsaid lifting bar, comprising a pair of jaws, one at least of which is provided with a smooth-faced friction button which is free to rock with the bar relative to the aw for making sliding and clamping contact with the smooth face of said bar.

2. In a hack saw machine thecombinat-ion of the saw lifting bar having one or more smooth faces and clamping and lifting means for clamping, lifting and releasing said lifting bar, comprising a pair of jaws, one at least of which is provided witha smooth-faced friction button which is free to rock with the bar relative to the jaw for making sliding and clamping contact with the smooth face of said bar, and means for adjusting the button relatively to the jaw to take up wear. A

3. In a hack saw machine the combination of the saw lifting bar having one or more smooth faces and clamping and lifting means for clamping, lifting and releasing said lifting bar, comprising a pair of jaws, one at least of which is provided with a smooth-faced friction button which is free to rock with the bar relative to the aw for making sliding and clamping contact with the smooth face of said bar, and an adjust able screw stud on the jaw upon which stud the button rocks.

4. In a hack saw machine the combination of the saw lifting bar having one or more smooth faces and clamping and lifting means for clamping, lifting and releasing said lifting bar, comprising a pair of jaws, one at least of which is provided with a smooth-faced friction button which is free to rock with the bar relative to the j aw for making sliding and clamping contact with the smooth face of said bar, said jaws and lifting bar having a relative angular movement and the said button being rotatable relatively to the jaws to partake of said angular movement.

5. In a hack saw machine the combination of saw frame, movable guide bar therefor, means for reciprocating the saw frame, a lift- &

ing bar for the guide bar and means for automatically clamping and liftlng sald llfting bar comprising a palr of aws and a pair of contact buttons carried by said jaws and having smooth faces bearing adjustably against said bar for making sliding and clamping contact therewith.

6. In a hack saw machine the combination of saw frame, movable guide bar therefor, means for reciprocating the saw frame, a lifting bar for the guide bar and means for automatically clamping and lifting said lifting bar comprising a pair of jaws hav ing recesses and loosely mounted friction contact buttons in said recesses presenting smooth faces which bear on smooth faces of said bar for making sliding and clamping contact therewith.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses this 26th day of October, 1911.

LEONARD M. FAIRBANKS.

itnesses:

GEORGE M. GUNN, Gr. F. THOMPSON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

